Radiation dosage on Lunar surface “safe for long-term human exploration”

Guest “Let’s light this candle!” by David Middleton

Moon safe for long-term human exploration, first surface radiation measurements show

By Adam Mann Sep. 25, 2020 , 2:00 PM

Moonwalkers take heart—China’s Chang’e 4 lander has made the first detailed measurements of the intense radiation that blasts the lunar surface and found that it’s safe for human exploration. The results give researchers a better idea of how much protective shielding future crews will need.

Astronauts on the Apollo missions of the 1960s and ’70s carried dosimeters to measure their radiation exposure, but the devices captured total exposure from their entire journey—not merely their time on the Moon’s surface. Ever since, scientists have had to estimate the radiation doses of crews bounding around on the lunar surface “from extrapolation and modeling,” says physicist Robert Wimmer-Schweingruber of the University of Kiel, a co-author of the study. “We’ve never actually measured them exclusively on the Moon.”

But there is renewed interest in taking such measurements, with NASA’s Artemis program intending to land crews for long-term stays by 2024 and the China National Space Administration eying human missions sometime in the 2030s. The robotic Chang’e 4 made history last year when it touched down in Von Kármán crater on the Moon’s far side, bringing a suite of instruments along for the ride.

[…]

The measured dose is about five to 10 times what passengers on an intercontinental flight from New York City to Frankfurt, Germany, receive when the plane is above parts of the protective atmosphere, Wimmer-Schweingruber says. Though high for Earth-based standards, radiation is one of the known dangers of spaceflight. NASA is legally prohibited from increasing the risk of its astronauts dying from cancer by more than 3%, and these levels remain below that.

What’s more, the researchers calculated that Moon bases covered with at least 50 centimeters of lunar soil would be sufficient to protect them. A deeper chamber shielded with about 10 meters of water would be enough to protect against occasional solar storms, which can cause radiation levels to spike dramatically. (Between the Apollo 16 and 17 missions, the Sun flared up in a way that could have caused radiation sickness, vomiting, and possibly death had astronauts been unprotected in space at the time.) Such a chamber would need to be reachable within 30 minutes, the amount of advanced warning time that is now possible with monitoring satellites.

[…]

Science
“Fig. 1 View of the Chang’E 4 lander with the location of the LND sensor head indicated by the red arrow.
LND is mounted in the Chang’E 4 payload compartment; the lid at the tip of the red arrow is closed at night to protect LND from the cold lunar night. Photo credit: Chinese National Space Agency (CNSA) and National Astronomical Observatories of China (NAOC).”

The full paper is available:

LND measured an average dose equivalent of 1369 μSv/day on the surface of the Moon. For the same time period, the dose equivalent onboard the International Space Station (ISS) as measured with the DOSIS 3D DOSTEL instruments (29) was 731 μSv/day with contributions only from GCR of 523 μSv/day. The additional ~208 μSv/day is due to protons while crossing the South Atlantic Anomaly. Therefore, the daily GCR dose equivalent on the surface of the Moon is around a factor of 2.6 higher than the dose inside the ISS. Because the Sun is currently still in an extended activity minimum (30), the dose rate from GCR reported here may be considered as an upper limit for human exploration of the Moon during conditions of low solar activity. Settlements on the Moon will provide additional shielding because they will be buried beneath layers of lunar regolith. While this would decrease the dose rate from charged particles, the absolute contribution from neutrons is expected to increase for shielding constructed from in situ resources, as borne out by measurements with the Apollo 17 Lunar Neutron Probe Experiment. These showed that the flux of thermal and epithermal neutrons increases significantly up to a depth of approximately 150 g/cm2(31).

LND measured the radiation environment on the surface of the Moon at this precision for the first time. In addition, due to the fact that we are now approaching solar minimum conditions, the contributions from GCR can be seen as upper estimations for the GCR dose. In the time period reported here, no SPE was observed from the surface of the Moon. Such events can increase the dose by orders of magnitude behind only thin shielding (32).

Zhang et al., 2020

Chang’e 4 is exploring “Von Kármán Crater, within the gigantic South Pole-Aitken basin“…

Figure 2. The Moon’s Farside Von Kármán Crater

The Apollo astronauts’ dosimeters measured the total exposure over the duration of the missions. So, it was not possible to separate the exposure during spaceflight from the Lunar surface.

Figure 3. SP-368 Biomedical Results of Apollo

The Apollo 14 astronauts (Alan Shepard, Stuart Roosa and Edgar Mitchell) received the highest radiation dose of any Apollo mission. 1.14 rads is 11,400 μSv, equivalent to about 8 full days of exposure on the Lunar surface. The radiation exposure for Apollo 14 was high because the launch trajectory took the spacecraft through the “through the heart of the trapped radiation belts” and a higher background radiation level than the other missions. Despite the radiation exposure, Alan Shepard set the record for the longest golf shot on the Moon.

Commander Shepard’s record still stands today, nearly 50 years later.

In December 2014, NASA conducted the first unmanned test flight of the Orion spacecraft, the type of spacecraft that will be used for the Artemis Lunar missions. Exploration Flight Test One completed two orbits, including a high orbit, twice transiting the heart of the Van Allen radiation belts.

Figure 4. EFT-1 NASA

Three hours and five minutes after launch, Orion reached its apogee and began its descent back toward Earth, separating from the second stage about 18 minutes later. The second stage conducted a one-minute disposal burn to ensure it didn’t interfere with the spacecraft’s trajectory. During the passage back through the Van Allen belt, Orion fired its thrusters for 10 seconds to adjust its course for reentry. At an altitude of 400,000 feet, the spacecraft encountered the first tendrils of the Earth’s atmosphere at a point called Entry Interface, traveling at 20,000 miles per hour (mph). A buildup of ionized gases caused by the reentry heating resulted in a communications blackout with Orion for about two and a half minutes. The spacecraft experienced maximum heating of about 4,000 degrees Fahrenheit, proving the worthiness of the heat shield. After release of Orion’s forward bay cover, two drogue parachutes deployed to slow and stabilize the spacecraft. Next followed deployment of the three main parachutes that slowed the spacecraft to 20 mph. Splashdown occurred 4 hours and 24 minutes after launch about 600 miles southwest of San Diego, California. A video of the Orion EFT-1 mission can be viewed here.

NASA

The cumulative radiation exposure was the equivalent about 10,000 μSv. Most of the exposure occurred during the roughly one hour the spacecraft travelled through the radiation belts.

References

Bahadori AA, Semones EJ, Gaza R, Kroupa M, Rios RR, Stoffle NN, Campbell-Ricketts T, Pinsky LS, and Turecek D 2015. Battery-operated Independent Radiation Detector Data Report from Exploration Flight Test 1. NASA/TP-2015-218575 NASA Johnson Space Center: Houston, TX http://ston.jsc.nasa.gov/collections/TRS/397.refer.html

S. Zhang et alFirst measurements of the radiation dose on the lunar surface.Science Advances. Published online September 25, 2020. doi: 10.1126/sciadv.aaz1334.

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d
September 28, 2020 2:09 pm

Let’s take our measurements during a solar minimum! That way they’ll all look the way we want them to whether or not they’re relevant.

Leif Svalgaard
Reply to  d
September 28, 2020 2:28 pm

Let’s take our measurements during a solar minimum
During solar minimum the cosmic ray flux is at the highest [except during strong flares].

September 28, 2020 2:18 pm

I’d like to know what the max UV Index (shortwave UVB) is on the moon. Will have to send one of these along on the next manned mission!

https://www.solarmeter.com/product/model65/

Robert of Texas
Reply to  UV Meter
September 28, 2020 3:52 pm

No! Send one of these! They are way cooler.

comment image

Joel O'Bryan
Reply to  UV Meter
September 28, 2020 4:01 pm

The Extreme UV environment of the space around the Earth is best seen by NOAA’s continuous monitoring of soft x-rays (solar X-rays in the 1-8 Angstrom (0.1-0.8 nm) range) currently with GOES-16. Damaging UV fluxes will follow this soft xray flux pattern extremely closely in the vacuum of space (no filtering) and down to the vacuum of the Lunar surface.

See here:
https://www.swpc.noaa.gov/products/goes-x-ray-flux

Reply to  Joel O'Bryan
September 28, 2020 4:29 pm

Didn’t know there was a UV flux relationship with <1 nm soft xrays. I'd also like to know 254 nm UVC intensity up there with no ozone layer or atm absorption. At sea level this UVC meter reads 0.0 µm/cm²… but atop Mauna Loa it reads 0.2 – 0.4 depending on sky clarity. In the picture it reads over 1600 to a UVC sterilization lamp.

https://www.solarmeter.com/product/model8/

Earle
September 28, 2020 2:36 pm

It sure looks like the radiation dosage trend is steadily upward. Is there anything climate change can’t do?

/sarc

September 28, 2020 2:45 pm

Anybody know the moon heat flux beyond 1.5 meters?

Earthling2
Reply to  Zoe Phin
September 28, 2020 7:26 pm

42 Ω

Joel Snider
September 28, 2020 3:13 pm

Yes, but is the moon safe from us – I mean, we’ve already left… dare I say it? FOOTPRINTS!

Peter W
September 28, 2020 3:22 pm

I heard some time ago from a medical professional that airline flight personnel have a higher incidence of cancer than the general population. They are being protected by the skin of the airplane plus a certain amount of atmosphere. How does this fit in with the information in the article?

Peter W
Reply to  David Middleton
September 28, 2020 4:13 pm

I read it before I posted. So what is your problem?

Ron Long
Reply to  David Middleton
September 28, 2020 6:10 pm

David and Peter, the issue of amount of radiation on “transatlantic flights” might be more complicated that MSHA will admit. On a commercial flight from Comodoro to Buenos Aires, Argentina (south to middle) two of us geologists had our pocket dosimeters go off, indicating an overdose. These were the quartz needle type of dosimeters, and they beeped quite loudly and the stewardess asked us to turn them off (can’t turn them off, so wrapped them up in coat and put in overhead). I don’t know if there was an unusual cosmic ray flux, or weakness in earths protective magnetic field, or what, but the dosimeters went off.

Michael S. Kelly
Reply to  David Middleton
September 28, 2020 8:48 pm

Odd that Apollo 7 and 8 had the same radiation dose, given that Apollo 7 never left low Earth orbit.

As for the neutron radiation from the lunar regolith overburden on lunar shelters, that’s where the money is to be made: Boron 10, with its thermal neutron absorption cross section of 5,000 barns.

There are more mundane hazards than radiation on the Moon. My college roommate and research partner, Dr. Kurt Sacksteder, measured flammability limits of materials from zero G to 3.5 G in very fine increments (work done at NASA/Glenn Research Center). The maximum flammability for any material occurred at 1/6 G – exactly the acceleration on the surface of the Moon.

Peter W
Reply to  David Middleton
September 29, 2020 5:22 am

In other words, you are objecting to me inserting a little real-life observational data into an article which talks of extended stays in space.

Clayton W.
Reply to  David Middleton
October 1, 2020 9:54 am

I was stationed on a Ballistic Missile Submarine back in the dark ages. One patrol the person with the highest exposure was the… Night Baker.

Turns out he used the microwave oven a lot for midrats (midnight meal) and the metallic braid on the door had worn some causing his exposure. When was the last time you checked the gaskets on your microwave? 🙂

2hotel9
Reply to  Clayton W.
October 1, 2020 1:14 pm

We actually replace microwaves pretty regularly. The interior paint finish on them is crap anymore so cleaning makes it start to come off and let interior begin to rust.

Joel O'Bryan
September 28, 2020 3:46 pm

No one who has studied the science and the data doubts that Lunar manned missions are possible with proper engineering of spacecraft and habitats and exposure monitoring and limitations set. Plus the Earth is a 3 day ride back to safety in the event the sun starts to show an extremely high coming solar activity if we can replace the Stereo missions to ensure good monitoring of the following side of the sun (solar longitudes about to rotate to Earth facing view). The big problem to avoid at all costs for lunar astronauts would be getting caught in mid-transit with the arrival of a very strong solar proton event hit from a solar X+ class flare/CME 24-48 hours earlier. If they are on the Moon they could go to a higher shielded safe compartment until the event passed.
The August 1972 solar storm, a storm that would have possibly lethally irradiated a transiting Apollo crew, hit right between Apollo 16 and Apollo 17 when no one one up there. Very fortunate for NASA.

The better, more relevant paper to read for a better perspective on this subject was published in July 2020.
“Galactic Cosmic Radiation in the Interplanetary Space Through a Modern Secular Minimum” published in the journal Space Weather.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019SW002428

This paper is worth a read for arm-chair solar enthusiasts. They discuss the probabilities and possible radiation related characteristics of comparing a SC25 as a Gleissberg minimum (1890–1920) or part of a lower probability Dalton minimum (1790–1830) and the impact on GCR environment for Lunar astronauts esch would have on radiation exposure

But note, at present there appears no way that a Manned-Mars mission of around 800 days appears feasible with current technology and radiation exposure limits in a mission design. So unless radiation safeguard limits are ignored and Mars-bound astronauts are prepared to either take the risk of dying in Space of acute radiation poisoning from a strong SEP event or back on Earth of bone marrow failure-neoplasia (lymphoma/leukemia, or aplastic anemia), manned Mars missions are not happening.

PCman999
Reply to  Joel O'Bryan
September 28, 2020 9:08 pm

Just have to travel faster to Mars on a proper nuclear powered spaceship. Ironic, huh? To avoid radiation related issues use an atomic craft.
Have spacesuit, will travel.

Ps: increase the amount of shielding and have the astronauts living in a module inside a water tank. Weight’s ok, they’ll have power to spare on the USS Robert Heinlein.

Joel O'Bryan
Reply to  PCman999
September 28, 2020 10:44 pm

Your solutions to the radiation problem are still far into the realm of science fiction novels.

Paul Penrose
Reply to  Joel O'Bryan
September 29, 2020 10:50 am

Of all the risks to astronauts associated with traveling to and exploring the moon, radiation exposure would seem to be one of the least. I also doubt that the kind of people that would be willing to take all those risks would regret their decision years later even if they got cancer.

Joel O'Bryan
Reply to  Paul Penrose
September 29, 2020 11:33 am

GCR-induced ion tracks across one’s retina would not be any fun. Acute radiation poisoning from high energy particles also has CNS effects which are awful. Chronic fatigue, inability to sleep, inability to concentrate, confusion/aphasia. If the whole crew is effected similarly all at once (likely), then loss of crew and mission could result in their inability to make/take time critical actions.

2hotel9
September 28, 2020 3:47 pm

This is something that was known a long time ago. Why is it”news”?

Joel O'Bryan
Reply to  2hotel9
September 28, 2020 4:07 pm

New data from an actual instrument.

2hotel9
Reply to  Joel O'Bryan
September 28, 2020 4:17 pm

Just because a new thermometer shows the same temps as an old one does not mean it is “new” information. NASA and multiple civilian sourced studies showed humans could occupy habitats on Lunar surface back in mid 1970s. How much of our tax money has been pissed away on saying the exact same thing repeatedly since?

2hotel9
Reply to  David Middleton
September 29, 2020 5:15 am

The Apollo landings had no instruments to measure radiation exposures of the astronauts? Find that rather hard to believe, does not seem like the sort of thing NASA would skip over back in the day.

2hotel9
Reply to  David Middleton
September 29, 2020 6:24 am

Same kind of dosimeter like I used in US Army, perhaps? Thats not especially confidence inspiring. I get the feeling those opposed to manned habitats and exploitation of resources on the moon would be able to poke holes in all this. I don’t see Chinese government being very concerned with how many of the people they send up dying from exposure, anyway. Think I would rather stick with NASA’s ’70s data, at least their goal was to not get people killed.

2hotel9
Reply to  David Middleton
September 29, 2020 7:18 am

Ahh, specificity. I know USGS released their geologic map of Luna a few months ago, have them or NASA mapped radiation sources on surface? That would have bearing on all of this, would it not? Protecting personnel and equipment from both sources would be a major issue. And would sources on/in the surface throw off any measure being made by instruments?

Robert of Texas
September 28, 2020 3:51 pm

Safe…LOL…on the moon. That was a good one.

The second one feels “safe” in an environment like that, one gets dead. It’s like cave diving (but worse). It doesn’t matter how many times you do it or how prepared you think you are, you are living right next door to death.

Joel O'Bryan
Reply to  Robert of Texas
September 28, 2020 4:04 pm

Hey there’s no COIVD-19 there so it must be safe. Right? Don’t even need a mask then.
I suggest we send Joe Biden to check it out. His brain is already fried, no no big loss.

David Blenkinsop
Reply to  Joel O'Bryan
September 28, 2020 4:50 pm

He’s used to staying in the basement though.

So, very helpful for reducing the radiation total dose.

Earthling2
Reply to  David Blenkinsop
September 28, 2020 7:42 pm

Except for Radon radioactive gas poisoning, as he has locked himself up in the basement for so long, now his brain is fried from terrestrial radiation sources. Or 47 years of swamp gas may also had some effect, which is now so obvious.

DonM
Reply to  Joel O'Bryan
September 28, 2020 5:32 pm

His brain isn’t fried, it’s just that it is so damn hard, recently, to get it out of neutral and into gear. And it’s very difficult to keep it from slipping out of gear.

We’ll see, tomorrow night, if Trump and his team, throw in just the right amount of goofy statements to distract poor idler Joe with his weird mental fixations. Things that include hairy legs, children & swimming pools; things that include milk truck drivers (and other truck drivers); things that include challenging people to push-up contests.

At the hello handshake Trump needs to whisper about a poolside push-up contest with a mean milk truck driver, as the impressed little girls watch. It will be 5 minutes before Joe will be able to clear his head of the fantasy.

2hotel9
Reply to  Robert of Texas
September 28, 2020 4:10 pm

“living right next door to death” Did exactly that several times in US Army, they got dead, I still be heres. 7 P Principle. Proper Prior Planning Prevents Piss Poor Performance. Not up to the cut? Stay on the porch.

Ian Coleman
September 28, 2020 5:49 pm

Not only are radiation levels safe on the Moon, they’re safe in Antarctica. Let’s establish a permanent colony there. It would be cheaper than establishing a base on the moon, and roughly as useful to actual human beings.

Robert of Texas
Reply to  David Middleton
September 28, 2020 7:45 pm

Which leads into the next really good question. Why are we in a hurry to send a person to Mars?

Maybe in 50 years the technology will be a lot more advanced, but sending someone in the next 20 is going to be very risky. We need to solve the problem with cost to get 1 pound into orbit for example. If we can bring that down far enough, we can send people to Mars in a ship encased in ice which has other uses should we need it. So I would put bringing down orbital costs right at the top of practical problems to solve.

I am all for exploration, but robots can be improved remarkably including their ability to leverage AI. We should be getting robots to Mars AND samples back repeatedly and reliably before we go sending people there- assuming we want those people back!

Paul Penrose
Reply to  Robert of Texas
September 29, 2020 10:59 am

Robert,
Because there is exactly only one planet (that we know of) that has human beings on it. We are one large rock from space from being exterminated. These types of events have occurred before and will again, it’s just a matter of time. Our best defense is two-fold: populate another planet, and develop better space-based technologies that can help us spot potential planet-killers and deflect them. Going to Mars will help us to achieve both goals. Failing to plan is the same as planning to fail.

Ian Coleman
Reply to  David Middleton
September 28, 2020 11:41 pm

Hello, Mr. Middleton. What do you want to explore Mars for? It’s a big round rock in the sky, and it’s a long way away, and nobody can live there at a cost of less than a hundred thousands dollars a minute. And we’re going there to harvest minerals and other resources? Come on. What would it cost to harvest them in an environment that cannot support human life? What would it cost to transport them back to Earth? There is no way you could turn a profit.

Why isn’t there a maternity ward in Antarctica? Why isn’t there a shopping mall? Well, because it’s a desolate place and no sane person would want to live there more than eight months at a time. Mars is, uh, considerably worse.

gbaikie
Reply to  Ian Coleman
September 28, 2020 7:45 pm

Unless permanent colony is another word for a prison, we have had permanent colonies in Antarctica for decades, and it hasn’t been cheap for US tax payers, nor very useful. The geniuses even tried to use solar power for energy.
Towns on Mars would cost US tax payers, nothing. And commercial lunar mining would lower cost to use the Moon. Very useful in comparison to having the permanent colonies at Antarctica for decades.

Ian Coleman
Reply to  gbaikie
September 29, 2020 6:50 pm

Hello gbaikie. “Commercial lunar mining?” What could you possibly mine on the moon that wouldn’t cost hundreds of thousands of times more than mining it on Earth? How would you even prospect for it, let alone mine it, amass it and send it back to Earth? If the surface of the moon were strewn with ten-pound gold nuggets, they couldn’t be mined for less than gold is mined on Earth.

Nobody who wanted to go to the moon in 1959 attempted to sell the moon landing as a commercial venture. The Americans put a man on the moon to show the Soviets who had the best society. It was all a giant vanity project which, soon after it had been achieved, was abandoned because it was of no further use.

Why are there astronauts at all? What good do they provide? When you ask space buffs that question they just look at you as if they can’t figure out why anyone ask such a question.

2hotel9
Reply to  Ian Coleman
October 1, 2020 7:56 am

Mining on Moon would not be for use on Earth, it would be for use on Moon and in orbital construction. Mining up there and shipping to Earth would be as useful as shipping laundry from San Francisco to Hawaii and back. And yes, that was done at one point.

Joel O'Bryan
Reply to  gbaikie
September 30, 2020 12:39 am

Eating lunar dirt or Mars dust to survive wouldn’t be much fun or useful calorie-wise Real hunger would set in quite quickly until the resupply of Earth grown food arrives.
You can’t eat an iPhone, so the saying goes for modern technology.

Clyde
September 28, 2020 6:06 pm

Far-Out-There Idea: Magnet Hole.

Drill a hole straight through the moon, pole to pole, insert metal tube. Drop magnets into tube until it’s full of magnets (they’ll fall gently, due to Lenz’s Law).

Et voila, you’ve got yourself a super-strong magnetic field which will encompass the moon and be more than strong enough to shield all but the most high-energy rays.

If we find that the core of the moon is still liquid, then drill as deep as possible from each pole. The first magnets dropped into the N-pole and S-pole tubes will lose their magnetism (and likely melt), but the ones above them which are cooler won’t, and as the core cools, those magnets which were above their Curie point will be re-magnetized by the magnets above them which were cooler… so the field will grow stronger as the core cools.

If the core is nickle-iron as is the Earth’s, it should pick up at least some magnetic moment due to the magnet-hole(s).

Thus, you’ve got shielding from high-energy rays without any on-going energy input needed.

Reply to  David Middleton
September 28, 2020 9:03 pm

I think we get at least a LITTLE bit deeper than 40 feet, David. (Waiting for the d’oh…)

Should be a touch easier on the Moon, though. No huge heat gradient, somewhat less maximum pressure to crush your drill string. (Haven’t calculated it, but probably still needs unobtainium for the last few million feet.)

Michael S. Kelly
Reply to  David Middleton
September 28, 2020 9:09 pm

In 1/6 G, things aren’t the same as they are on Earth. Aluminum oxide has a maximum compressive strength of 798,000 psi, and a maximum density of 0.144 lb/in^3 (I use real units, rather than SI, because I went to Purdue). The maximum height of a constant diameter column of Al2O3 on Earth would thus be 5.54E6 in, or 462,000 feet. For a linear tapered column, the maximum would be 1.39E6 feet.

Naturally, one could never get to those values on Earth. But on the Moon, where there is no wind loading and no seismic activity, all bets are off. A maximum column height of 8.3E6 feet (1,372 nmi) would be doable – just barely.

Since you could go UP 8.3 million feet, you should be able to go DOWN 5.699 million feet (the distance to the Moon’s center, after which it is all up hill).

Given that the Moon doesn’t have a core of liquid hot magma, I don’t see why this would be impossible. But I don’t know why anyone would try it, other than “it’s there.”

Just drill down a couple of miles, and drop some really strong NIB magnet disks down there, and see what happens.

Joel O'Bryan
Reply to  Clyde
September 30, 2020 9:40 am

A lunar magnetic field would trap electrons and protons and create belted radiation zones. Very much like Earth, except without the atmosphere to create aurora by intercepting pole descending electrons. Thus the lunar poles, where we want to mine ice for water, would get a constant stream of electrons. It’d be like living in a cathode ray tube target as the concentrated electrons came spiraling down the field lines to the lunar polar surface.

Latitude
September 28, 2020 6:56 pm

10 meters of water?….somehow I think they better solve that problem first

Nashville
September 28, 2020 8:09 pm

NASA is legally prohibited from increasing the risk of its astronauts dying from cancer by more than 3%
Where did this come from, and how can it possibly be measured?

Joel O'Bryan
Reply to  Nashville
September 28, 2020 11:00 pm

yeah. The 3% limit seems to hav escaped everyone here. I read about that limit years ago. Still I laugh at all the suggestions and write-ups that a Manned Mars is feasible… clearly not with 3% limit. No way in Hell.
Loss of Crew (LOC) scenarios during a SEP are way too likely in most scenarios, either during the transit out to Mars or the transit back to Earth. And then there’s the GCR problem during Solar minimums that on Mars makes it 100x worse than Earth at polar latitudes. Ion Tracks on retinas would be no fun. Then ther’s insidious CNS efects of fatgue and loss of focus from neutron radiation. Death.

Joel O'Bryan
Reply to  David Middleton
September 29, 2020 10:49 pm

NASA/GISS was created in the mid-60’s to study these Space Weather problems. Sadly, Hansen took them in other directions in the 80’s to the chase glory in the climate scam. GISS should either be defunded or re-directed to its original mission.

Clyde Spencer
Reply to  David Middleton
September 29, 2020 7:37 pm

I presume the probability of developing cancer is based on the “Linear – no threshold” assumption. Question: Do Tibetans or those living in the high Andes have elevated cancer rates? For that matter, do those living in the Denver environs have cancer rates greater than Cajuns living in the bayous?

The Original Clyde, with a last name

nc
September 28, 2020 10:54 pm

Why send a human to the moon to find Alice or Mars. With the advances in AI and robotics, much simpler to send a machine than supporting a human. Look at the time and resources required to support life in the space station.

Vald
Reply to  nc
September 28, 2020 11:40 pm

I agree, humans in space are only a waste of time and money.

Joel O'Bryan
Reply to  David Middleton
September 29, 2020 10:42 pm

Abilities are subjective.
A team of human geologists on Mars would need lots of TLC compared to a team of geologists in Pasadena. Geologists sitting around a conference table looking at 2 hour old Mars rover imagery to decide which rock to command the rover robot to pick up and save for a return mission sounds pretty good compromise to me.

Personally, the coffee sipping, enjoying-a-nice-day in Pasadena geologist sounds a lot better to me than 800 days in a hot space suit, eating freeze-dried rations, as a geologist while getting irradiated is a real shit job when a robot could just be commanded to do it. The super HD resolution cameras on the robot rover and other sensors can far exceed the limited observational capabilities of a human Mk1 eyeball to determine which rocks to save.

sabretache
September 28, 2020 11:20 pm

Perhaps someone here can explain why no human has ventured further than relatively low-Earth orbit (ie has not transited the Van Allen belts) since the moon-landings 50 years ago. Have they run out of that magical gold foil ubiquitous in the moon pics and which apparently substituted for the several inches of lead shielding that would otherwise have been required to prevent a fatal dose of radiation to mere flesh and blood?

Paul Penrose
Reply to  sabretache
September 29, 2020 11:05 am

Stop bothering us with your ignorant prattle. Don’t you have anything better to do with your time, like building a steam rocket to prove the Earth is flat or something?

September 29, 2020 12:26 am

Having just read ‘Wagging the Moondoggie’ – just Part One is sufficient – I am even more convinced man has never walked on the moon, probably never gone beyond low earth orbit. Those VH Belts remain an insurmountable problem. I’ll eat my hat if we make it in 2024. Had we already done it, and done it several times using 1960/70s technology, why would this information be of any interest whatsoever in 2020?

Tarrasik
Reply to  David Middleton
October 1, 2020 4:18 pm

What’s nonsensical is seeing astronaut footprints in the soft lunar dust, right under the lander’s three foot diameter rocket nozzle. Or NASA losing 700 boxes of original tapes and data.

bonbon
September 29, 2020 2:19 am

Mars with fusion engines, maybe with He3 from the Moon will work. A few weeks transit.

The crash-program investment needed is beyond any Elon Musk type billionaire, giving new meaning to NASA.
Spinoff, fusion power here. And the solar system at such sustained acceleration will look different.

The current financial system is doomed anyway, so light a fusion candle!

Theo Richel
September 29, 2020 4:46 am

My attempt to fight radiophobia on planet Earth: https://youtu.be/JpcUCo0ebNA

The Dark Lord
September 29, 2020 8:28 am

yes but can sars-cov2 survive on the moon ? that is the pressing question right now …

accordionsrule
September 29, 2020 3:26 pm

Yeah, but they get away from 5G, so it’s a wash 😉

Sobaken
September 29, 2020 11:44 pm

Somehow we consider 57 μSv/h to be safe on the Moon, but much lower radiation levels on Earth (like in Chernobyl and Fukushima disaster zones) to be very dangerous. People absolutely freak out when they see even tiny increases like 0.5 μSv/h as if that’s the end of the world

Joel O'Bryan
Reply to  Sobaken
September 30, 2020 12:32 am

“safe” is always a relative term.

Brandon
October 1, 2020 4:45 pm

You first

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